Imagine a monomaniacal businessman who inherited loads of cash from his father, treats women like property and races around with no master plan, barking kooky sentence fragments. At first it’s funny and then it gets sad and then it gets tiresome.

No, I’m not talking about the president-elect of the United States. I’m talking about Howard Hughes as portrayed by Warren Beatty in Rules Don’t Apply.

Written and directed by Beatty himself, this strange and certainly energetic film has just enough self-deprecation in its DNA to suggest, yes, it is aware that this is a vanity project of Olympian proportions. But then it goes ahead and has 27-year-old Lily Collins fling herself at 79-year-old Beatty, even though she’s a proud, church-going virgin. (To be fair, she does have some champagne.)

Rules Don’t Apply is an odd and exasperating film, and just thrilled to play in that tiresome sandbox of the late 1950s/early 1960s, when white male voices were the only ones that mattered. But there are long stretches that are brisk and peppy and quite entertaining. It doesn’t make sense as a comedy, it doesn’t quite work as a drama, and it doesn’t follow the typical roadmap of a biopic, but Rules Don’t Apply is strangely compelling nonetheless.

Beatty’s Hughes is the center of gravity, but the lead, at least on paper, is Alden Ehrenreich’s Frank Forbes: a Henry Hill-like newcomer to Hughes’ whirlwind world of idiosyncrasies.

Forbes is one of many drivers Hughes keeps on staff, primarily to chauffeur his contracted Hollywood starlets. (One of Hughes’ many businesses was running RKO Pictures.) Each of his new discoveries is situated with a weekly paycheck, a furnished home and a promise that, yes, eventually they will end up on screen. Everyone’s getting fed so few balk at the arrangement, even if they’ve never met the boss face to face. The only rule: the drivers and the talent mustn’t fool around.

When the newest ingenue comes to town (Collins’ Virginian Marla Mabrey), the time must come to see if – ahem – rules don’t apply. (Yes, Ehrenreich is condemned to actually say the line, but what’s worse is that Collins has to sing it.)

The first half of the picture is a great deal of fun. Everyone is beautiful and wearing great outfits and Marla’s house overlooks the Hollywood Bowl, so the Philharmonic is right there to score some of the more tender scenes. (It’s always nice when Mahler’s 5th Symphony is wafting on the breeze.)

But eventually both Frank and Marla get more involved directly with Hughes – and that’s when Beatty’s indecision over the film’s tone creates turbulence. Hughes’ eccentricities are played for laughs like Alec Baldwin’s 30 Rock character Jack Donaghy, even after it becomes clear his psychological disorders are no joke. There is a central sequence in which Hughes and Marla sit in the dark and volley banter for an interminable period, with every one of Beatty’s stammers becoming more unintentionally cringeworthy.

Frank and Marla’s chaste forbidden romance (both are religious, as well as keen to keep their jobs) seems like it will be the central conflict of the movie, and for a while it is – but then Beatty hogs the spotlight for the second half of the film. His mania drags the setting from Hollywood to Las Vegas to Managua and Acapulco, but these “boss from Hell” scenes, while not bad, are far less interesting than the chemistry between Ehrenreich and Collins, a storyline that is altogether dropped until the very end. (It’s here I’ll point out that Rules Don’t Apply is one of the few motion pictures in which premature ejaculation is a pivotal story beat.)

A slew of big names show up in small roles to work with Beatty in what will likely be the not-very-prolific legend’s final film. It’s fitting in a way that one of the key forces behind New Hollywood, the movement that overturned the old studio system, should go out in the guise of one the last true moguls. But Hughes wasn’t just about Hollywood, so that’s yet another thing about this movie that refuses to snap nicely into place.

The title would have you believe that a story this extraordinary will still be magical even if the pieces don’t all fit. But to elevate from merely interesting to truly great, perhaps some rules do apply.